Optical flow estimation in gated cardiac SPECT

In cardiac gated SPECT, image reconstruction suffers from several degrading factors including limited data counts, depth-dependent blur, attenuation, scatter, and motion blur. In our recent work it was demonstrated that use of motion-compensated temporal processing could lead to improved accuracy in 4D reconstruction. In this work we investigate how different optical flow estimation methods can affect the reconstruction in 4D, and in particular, we examine how much room is still left in optical flow estimation toward improving the reconstructed image quality. In our experiments we conducted a thorough, quantitative evaluation using simulated imaging study with multiple noise realizations from the NCAT phantom. As an upper bound, the known motion in NCAT was used for reconstruction. The results show that 4D reconstruction with a periodic optical flow model can achieve results almost matching that from the known motion.